The incorporation of replaceable cylinder liners in the design of an internal combustion engine provides numerous advantages to the manufacturer and user of such an engine. For example, replaceable liners can be easily removed and replaced during overhaul of the engine. Additionally, cylinder liners eliminate the necessity to scrap an entire engine block during manufacture should the inside surface of one cylinder be improperly machined. To assist in maintaining the liners in place within the cylinders during use, some conventional liner and cylinder configurations employ a stop (e.g., top-stop, mid-stop, bottom-stop) on which rests a seat formed in the liner.
Despite the above and other advantages, numerous problems attend the use of replaceable cylinder liners, as is exemplified by a large variety of cylinder and liner designs previously used by engine manufacturers. While each of the previously known liner designs may have demonstrable advantages, no single design appears to be optimal or void of problems and shortcomings.
For example, conventional engine systems with cylinder mid-stop and liner seat configurations suffer from several shortcomings. For example, significant cylinder and liner distortion can be experienced at the cylinder mid-stop and liner seat interface during operation of the engine.
The distortion of the cylinder and liner can induce relative motion between the cylinder and liner at the interface between the mid-stop and seat, which causes excess wear on the mid-stop and seat. The excess wear may negatively impact the performance of the engine, and in some instances, require replacement of the entire engine block. Some conventional engine systems position an annular shim between a top-stop and liner seat to reduce wear between the top-stop and seat. However, conventional engine systems with a mid-stop configuration have not employed an annular shim. Additionally, for those engine systems that do utilize shims between the liner and cylinder, the shims can be difficult to install and align with the liner during assembly. Such shims often are installed after original assembly of the engine, such as during a repair or reconditioning of the engine. For this reason, most shims are not well suited for installation during the original assembly of the engine.
Additionally, the distortion of the cylinder and liner may cause the liner to protrude into the cylinder cavity. Protrusion of the liner into the cylinder may cause the liner to impact the piston causing wear and deformation of the piston.